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Overall mileage is 21.7 mpg. Mileage on interstate highway driving trips has been between 23.3 and 23.8 mpg. I don't know what some people do to achieve some of their dreadful fuel economy .. maybe a defective car or just a left foot made of lead?
The RDX isn't perfect but a gas guzzler it is not.
Fun files when you're having time!
My average is around 17 mpg but half of it is in downtown Los Angeles: most horrible traffic in the US........
- Turn off the AC, the unit probably runs in a constant "defrost" mode;
- My RDX has a dealer installed roof rack. Noticed that the cross members seemed backwards on roof rails. Although the idiot proof directional errors suggested that this was the correct configuration, the aerodynamics seemed backwards. Reversed the direction of the cross members and noticed that the bottom of the ends of the cross members are now aligned parallel with roof rails. (As installed by the dealer the bottom end of cross members and roof rails are at an angle, which made think the rack was incorrectly installed when inspecting. :lemon: ) However, noticed there was a considerable amount of wind noise with the cross members installed. Decided to only use the cross members when needed on trips. You need a 30T Torx to remove just four screws. Really do not know if reversing cross members made a difference, but removing all together probably does.
- Turn on the instant MPG indicator and drive with that indicator on for a while. Seems like the drive train is tuned to keep the engine at lower RPMs, which means the turbo constantly engages to boost torque. Also noticed that downshifting one gear with the paddle in D before accelerating brings up the RPM but not the turbo boost. Probably a zero sum gain for MPG. However, it almost seems better to punch it and coast to get better gas mileage in this car.
After this last highway trip the engine does seem a bit looser. The true test will be on Monday during rush hour.
Hope this information helps. The car is a blast to drive -handles like a sports sedan through the curves and is awesome in the white slippery stuff. All in all the gas mileage is not that bad considering the range of the driving experience. I am extremely satisfied with my purchase Sound system is awesome:)
Until there are advances in technology, there will always be a MPG price for performance and four wheel drive. This drivetrain nimbly moves a lot of weight very quickly when needed.
Not sure which way you were installing them, but the correct direction of the crossbars would put the fat rounded edge facing forward and the sharp edge facing backward, just like an airplane wing. If reversed, they will definitely be noisier and have more drag.
I am very pleased with the sportiness and handling of the car. So the MPG is a very minor issue.
It's just a mystery as to why it gives me the same 17 MPG for the same driving as my V8 4.5L BMW...
At least you can take comfort that you did not shell out an extra $20,000 for a new B'mer. Feel sorry for the folks who spent ten grand more for a Lexus RS 400h hybrid and still get 18 MPG with a much more complex drivetrain.
There might be a lesson to be learned about engines here. 18 MPG for the CX-7 does not give me a warm fuzzy either.
Sorry, its a 12minute video but if you press pause, go fix a sandwich and some lemonade, you could just fast forward to the good parts.
Like the accord in 95 changing to 1996, I hope acura redoes the lower front end and add some of the TSX'S underbody coverage. The TSX has a Drag Co. of .27 and I am unsure of the RDX's drag co.
I guess investing in some things to fix/cover the gaps in the underbody should boost aerodynamics (thus acceleration and MPG )
-Cj
I am a mechanical engineer and aerodynamics researcher, and the first time I saw that video months ago, I was really mortified at their lack of knowledge/expertise in the area. Generally, whenever they say stuff like "we'd like to see" it means they are not understanding the mechanicals or the aerodynamics. I definitely trust the Honda engineers over the TOV guys in this regard. For one thing, you can't evaluate aerodynamics correctly without wind tunnel testing or computational fluid dynamics. A video camera and pointer doesn't cut it, especially without expertise!
There is a fundamental difference between the TSX and RDX, and that is the profile and aspect ratio. Much of the RDX's drag comes from the large base area and abrupt closure on the back end. It's a classic "bluff" body shape. Fundamentally, the TSX is better with a long sloping rear window and smaller base area. What this means is that the RDX will be far less sensitive to underbody tweaks than the TSX. Even with a smooth underbody, the RDX would still have a lot of base drag dominating the overall drag total. That said, I have looked under my RDX, and don't see a whole lot of additional tuning to be done anyhow. They have a small chin deflector on the very front that takes care of the incoming flow for the most part. Most of the other stuff, even stuff that looks draggy, is well within teh vehicle profile and not really out in the airstream. That tells me Honda did do some wind tunnel testing and took care of the major issues.
Finally, I am getting 22-25mpg on the highway (72-75mph) in my RDX. Highway speeds are where the drag really matters. The people who are seeing poor gas mileage are seeing it in city driving, where aerodynamic drag is much lower and driveline friction and powetrain efficiency is more important. The RDX definitely gets lousy gas mileage in city driving conditions, but that is not impacted by aerodynamics to a significant extent.
So anyways, take the TOV video with a big grain of salt. This is the 3rd or 4th video I have seen where I really question their qualifications. It just doesn't pass for professional level engineering/aerodynamics expertise.
Craig
Hope you're enjoying your RDX! Sadly, no acura comes in my favorite color any more(Deep Green Pearl). They dropped it from the lineup. :sick:. I think it would be a great match to the RDX with a Beige interior.
-CJ
Also been experimenting with the paddles and getting the revs up. Man this thing will haul when you drop a gear. I think with some computer mods, the RDX would be scary fast. I think Acura has under tuned the potential power of this car down for liability reasons. Have felt the SH-AWD kick in on few twisty roads. It is like someone suddenly pushed to the vehicle through the turn. Cool, but I still don't know if I trust it.
The RDX is a great car. However, $3.00 gas is insane for any car. Since no one seems willing to buy my perfectly good 91 Integra, I may dust that thing off if gas prices get too bad. If the RDX lasts as long as that car, I will be one satisfied customer.
1) zero-out the mpg while driving in the open freway at 70 mph. The Max mpg I get in my RDX is 24. My V8 4.5L BMW (RWD) gave 27 mpg or so for the same experiment.
2) idle for 30 minutes. The RDX burns say 0.5 Gal. The BMW would burn 0.4 Gal or so.
Experiments (1)and (2) above seem to imply that this mpg might not be a function of the drive train! Because when you go straight in the freeway the SH-AWD puts most of the power on the front wheels.
Still I love my RDX, great performance. But the MPG is just an engineering mystery........... :confuse:
First gear in the RDX is a crazy short 12.23 with the final drive. The 4.533 final drive is old school muscle car drag racer short. The fifth gear is 2.77 with final drive, again, very short.
For reference, a Corvette with an automatic:
First gear: 10.29
Sixth gear: 1.72
Now for a closer competitor, a BMW X3 with an automatic:
First gear: 18.07 (!!!!)
Sixth gear: 2.97
So you can see, the BMW has similarly short gearing, and gets similarly poor milage (browse some of their forums to see the same complaints). The six speed allows the BMW to be in first gear for less time which helps a bit.
Why? For that 7 second 0-60 in a 4000 lb vehicle.
I would love to get a TSX as my next car as it is a revver but I think honda/acura should be working day&Night on a 6-7speed automatic that cruises in 6th gear at around 2k-2.6k RPM. It saves gas and let others "Play" in the 4-5 gears. Watching the tac go from 6 o'clock to 3 o'clock seems cool occasionally but not always.
-Cj
Just an amateur guess: Putting too small of an engine in a vehicle can be almost as bad for mileage as a giant V8, or even worse. I don't understand putting a 4cyl. in a vehicle of that size & weight, with AWD yet--it doesn't make sense to me.
FWIW, I have a bmw 5-series (6 y.o. e39) RWD wagon, 6 cyl, auto, & I average around 18.5 mpg around town, & 23 HWY. Obviously, it will get better mileage than a comparable vehicle with AWD. But since the cargo capacity is a bit more than the RDX, frankly, I'd rather get the better mileage & put on snow tires in winter.
I'd love to know why Honda felt compelled to put a 4 cyl. in a vehicle of that size.....??
In comparison, my BMW 540 (V8) had a lot of aluminum parts, which made it 1,000 lbs lighter.
I don't think the AWD is a major factor. Think of the Murano analogy: the AWD is only 1 MPG lower than the FWD. They weigh 3,950 and 3,800 lbs respectively. Hence, 18 MPG and 19 MPG.
I was getting 17.5 MPG with my BMW; the RDX gives me around the same.
The V-6 sounds good, but all the V6 SUVs in this range have poor acceleration: Lexus RX, Murano, Highlander, are much slower.
Hence, I am happy with the current RDX engine performance and handling.
I do think those of you who are getting the 13 mpg average do have something going on causing it. Perhaps the reason Acura is not doing anything is because the engine may still be within normal operating specs to them. However, if I were getting that low of mileage I would be highly upset also. Hopefully, Acura/Honda will be able to come out with a fix.
I don't know what lofty engine specs are normal for you, but most shoppers see a big difference between the RDX and CR-V in terms of power and general sport feel. I know I did. The RDX is certainly not super fast and it's not a sports car despite what some people may think, but it's no slouch either. It's one of the best handling SUVs I have driven, and the powertrain is decent. 0-60 times in the 6 second range are still pretty good for a realistic SUV nowadays.
People on here keep saying "well my other car didn't do this bad and I drive them both the same". Is your other car TURBO'D? If you have a firm foot off the line, doesn't have to be heavy, just firm til you hit second or third. On a turbo'd vehicle, you are engaging the turbo that much more which uses more gas. The whole idea for the reduced lag is to get the turbo goin sooner so you dont have to dip into the throttle that much. If you don't change your style of driving, you will get crappy mileage if you drive the way I explained.
One more thing on the turbo. It is ALWAYS spinning which means you will use a bit more gas, even at low throttle or cruise.
If Acura was REEEEALLY serious about addressing this problem they would do well to do one of a few things. One, put a better variable geometry turbo in. They make models that vary intake across all driving conditions and dont open and close one valve when a certain parameter is reached. This one has vanes that turn to allow the ideal flow for just about any driving condition. Another idea, one mentioned, is to adjust the tuning or have a knob that adjusts it for you, maybe even allow a lower octane or just tune for 89 instead of 91. The reason 86 or 87 doesn't work is because the ECU can't accomodate that degree of a difference and running for extended periods on this will hurt the engine. 89 on and off from 93 won't hurt anything. All the time, maybe it'll do some damage. One last thought that might help not with mpg, but range, is a bigger tank. Just a few more gallons as weight will become eventually become a concern.
I don't own one but am seriously looking. What is the break-in instructions for the car? I see people who have to drive other cars a set amount of miles UNDER a certain speed in order to properly break the engine in. I'm curious if this has any bearing on what some people are doing. People are saying they do several hundred mile trips on a BRAND NEW car. That doesn't sound like a great idea to me. Any thoughts?
There have been numerous variable nozzle / variable vane turbo designs over the years, but none have proven reliability or longevity -- they have too many delicate moving parts in a hot exhaust gas stream. One of Honda's stated goals was to make the RDX turbo simple and reliable, something that should last a long time. They just would not be able to achieve that goal with the more exotic variable geometry turbo designs. I believe that's why you never see those in production automobiles nowadays. In fact the last application I remember was one of Shelby's turbo Dodges back in the late 80s or early 90s.
I actually appreciate that the RDX has a couple more gallons in the tank than my last similarly sized vehicle. It means I can realistically go past 400 miles on a highway trip, something I could not do before.
The RDX has a 600 mile break-in period. They give the usual guidelines: no hard stops, moderate acceleration, no constant speeds for long periods of time, etc. There would be nothing wrong with short highway trips as long as you make an effort to vary speed once and a while.
1989 Shelby CSX-VNT
BorgWarner makes one built for the 2006 Porsche 911 Turbo.(last paragraph)
About the only time the turbo would be "free-wheeling" would be at idle. With any throttle input the turbo provides some form of boost as the exhaust side impeller would be spun. From what I understand the blow-off valve on a turbo doesn't work like the by-pass valve on a blower allowing a no boost condition under cruise. It just protects from an over-boost condition. I might be wrong, my knowledge of turbo's isn't as good as on blowers. I didn't mean to say that it is ALWAYS under boost, I meant under lighter throttle conditions, it is still providing some form of boost which uses more fuel. Even only a few pounds of boost still uses a noticeable bit.
There's no way I would be getting 25mpg in this vehicle on the highway if it was boosting significantly all the time.
Amount of boost requested is directly controlled by the amount of throttle opening. Ability of the turbo to generate the desired boost is directly related to engine RPM - higher RPM = better ability to generate high boost.
This is why many turbo engines have lag at low RPM - high boost is requested, but the turbo can't spool up enough to provide it until the engine revs up. Newer engines usually have very good low-RPM torque characteristics to offset the initial turbo lag.
I guess what I'm driving at is if this is a large four cylinder, shouldn't this thing be getting a little more than 21-23mpg(as opposed to your 25 which apparently is NOT the norm, I think you're experience with previous turbod vehicles gives you an advantage on how to drive for mpg(note: this is just an opinion))? I'm just trying to see where this drain on mpg is on the highway. If you're getting 25 fairly consistently I'm assuming, what are other people doing that they aren't? Not feathering the throttle enough during cruise?
After a little more thought, the biggest thing might just be weight. Compare it to the RAV4 which is aerodynamically similar, 4 cylinder engine, the most glaring difference appears to be weight. The Rav is 400lbs LIGHTER and it's rated at 27mpg highway. Seems to me that may be the biggest reason.
All said and done, the biggest culprits in my opinion, are a heavier suv and less skilled drivers or less mpg road conditions(ie alot of hills). As I said, if someone here can consistently get 25, where's the problem? Doesn't seem to be completely the cars problem if the turbo isn't as involved as we've discussed. Just seems to be a HEAVY turbod car with people that aren't as consistent on the throttle as they think or live in slightly hillier areas.
Also, the RDX 4-cyl spins a lot faster on the highway than the Rav4 V6. A slower spinning engine results in more complete combustion of the air-fuel mix, in turn resulting in better fuel efficiency.
Plus, the Toyota/Lexus 3.5L V6 is an absolute gem when it comes to power and efficiency, whereas the RDX 2.3L Turbo is a new and unproven engine. I'm sure Honda will make it more efficient over time.
Add all of this up, and there's the MPG gap.
"the RDX is also wider (73.6" vs 71.5") and has wider tires, resulting in more aerodynamic drag." Umm, no. Drag is figured by surface AREA, but it is also figured by drag coefficient. For arguments sake I took the two as boxes and just figured out their general area based on specs given on this site, the Rav is 32.92 sq ft, the RDX is 33.32. Only .4 sq ft of difference. The Acura is also shorter and sits lower to the ground which also has an effect on drag. Now you can argue the tires are wider as well, but with these numbers, can you really tell me there is that much of a difference? The drag coefficient of the Rav 4 is .33, I doubt the RDX's is worse than that which should makeup for the slightly larger area(it's not listed anywhere I can find). These two vehicles are as close as you can get in terms of overall dimensions. The only glaring difference is that the RDX weighs 456 lbs more(#'s from this site). You may have a point on the tire tread, but I don't know nearly enough to comment on that.
Yea, I know it's a crapshoot trying to find the losses. The more you dig the better you make the car though, right? It still just seems that the RDX is a bit heavier and just needs a finer touch if driving for mpg. If they can lighten it, I'm sure that will make up the difference in MPG.
2.AWD (all wheels driving the vehicle) :surprise: 3.Tires (18" High Performance All Season) and 4.Gear Ratio (4.533-Great for acceleration not for crusin') :mad:
As for the number of gears, 6-spd transmissions don't always use the 6th gear as a high speed cruising gear -- in fact they normally increase the number of gears to result in tighter gear spacings, not a taller cruise gear. Whether it's a 4,5,6,7 speed is not directly relevant to the rpm/mph at highway cruise -- the overall ratio in top gear is what matters. I have a 6-speed sports car and it actually turns around 4000rpm at 75mph.
The reason the RDX can pull 1,900 rpms at 70 mph is because of all the low end torque it has. It has a flatter torque curve then just about any production honda engine. I think it is the first time honda has had an engine make more torque then horsepower. A little bit of tweaking might even allow a slightly lower, numericaly speaking, 6th gear as well.
By using a 6 speed tranny though could tighten the gear ratios up some giving a slightly lower rpm in each gear and smoother shifting.